Practice Questions

Q17.A metallic surface is illuminated with radiation of wavelength 𝜆, the stopping potential is 𝑉0. If the same 𝑉0 surface is illuminated with radiation of wavelength 2𝜆, the stopping potential becomes . The threshold 4 wavelength for this metallic surface will be (1) 3𝜆 (2) 4𝜆 (3) 3 (4) 𝜆 2𝜆 4

Q17.The half life of a radioactive substance is 𝑇. The time taken, for disintegrating 7 𝑡ℎ part of its original mass will 8 be: (1) 2𝑇 (2) 3𝑇 (3) 𝑇 (4) 8𝑇

Q17.Ratio of thermal energy released in two resistor R and 3R connected in parallel in an electric circuit is : (1) 3 : 1 (2) 1 : 1 (3) 1 : 3 (4) 1 : 27

Q17.The equivalent resistance between A and B as shown in figure is: (1) 10 kΩ (2) 5 kΩ (3) 20 kΩ (4) 30 kΩ

Q17.A proton moving with one tenth of velocity of light has a certain de Broglie wavelength of 𝜆. An alpha particle having certain kinetic energy has the same de-Brogle wavelength 𝜆. The ratio of kinetic energy of proton and that of alpha particle is : (1) 2 : 1 (2) 4 : 1 (3) 1 : 2 (4) 1 : 4 JEE Main 2023 (01 Feb Shift 1) JEE Main Previous Year Paper

Q17.The de Broglie wavelength of a molecule in a gas at room temperature 300 K is 𝜆1. If the temperature of the gas is increased to 600 K, then the de Broglie wavelength of the same gas molecule becomes JEE Main 2023 (10 Apr Shift 1) JEE Main Previous Year Paper 1 (1) 2𝜆1 (2) √2𝜆1 (3) 1 (4) 2𝜆1 √2𝜆1

Q17.The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper (1) 𝐷 (2) 𝐴 (3) 𝐵 (4) 𝐶

Q17.The equivalent resistance between A and B is _______. JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper . (1) 2 Ω (2) 1 Ω 3 2 (3) 3 Ω (4) 1 Ω 2 3

Q17.In a Young’s double slit experiment, the ratio of amplitude of light coming from slits is 2 : 1. The ratio of the maximum to minimum intensity in the interference pattern is (1) 9 : 4 (2) 25 : 9 (3) 2 : 1 (4) 9 : 1

Q17.A single slit of width a is illuminated by a monochromatic light of wavelength 600 nm . The value of a for which first minimum appears at θ = 30o on the screen will be : (1) 1. 2 μm (2) 3 μm (3) 1. 8 μm (4) 0. 6 μm

Q17.A small object at rest, absorbs a light pulse of power 20 mW and duration 300 ns. Assuming speed of light as 3 × 108 m s-1. The momentum of the object becomes equal to : (1) 0 . 5 × 10-17 kg m s-1 (2) 2 × 10-17 kg m s-1 (3) 3 × 10-17 kg m s-1 (4) 1 × 10-17 kg m s-1

Q17.The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by 50%. The percentage change in voltage sensitivity of the galvanometer will be : (1) 100% (2) 50% (3) 75% (4) 0% JEE Main 2023 (31 Jan Shift 2) JEE Main Previous Year Paper

Q17.A uniform metallic wire carries a current 2 A, when 3. 4 V battery is connected across it. The mass of uniform metallic wire is 8. 92 × 10−3 kg, density is 8. 92 × 103 kg m−3 and resistivity is 1. 7 × 10−8 Ω −m The length of wire is : (1) l = 6. 8 m (2) l = 10 m (3) l = 5 m (4) l = 100 m

Q17.Different combination of 3 resistors of equal resistance R are shown in the figures. The increasing order for power dissipation is: (A) (B) JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper (C) (D) (1) PB < PC < PD < PA (2) PC < PD < PA < PB (3) PC < PB < PA < PD (4) PA < PB < PC < PD

Q17.A point charge of 10 µC is placed at the origin. At what location on the X -axis should a point charge of 40 µC be placed so that the net electric field is zero at x = 2 cm on the X -axis ? (1) x = 6 cm (2) x = 4 cm (3) x = 8 cm (4) x = –4 cm

Q18.The H amount of thermal energy is developed by a resistor in 10 s when a current of 4 A is passed through it. If the current is increased to 16 A , the thermal energy developed by the resistor in 10 s will be (1) H (2) 16H (3) H (4) 4H 4

Q18.Speed of an electron in Bohr’s 7th orbit for Hydrogen atom is 3 . 6 × 106 m s-1. The corresponding speed of the electron in 3rd orbit, in m s-1 is : (1) 1 . 8 × 106 (2) 7 . 5 × 106 (3) 3 . 6 × 106 (4) 8 . 4 × 106

Q18.If each diode has a forward bias resistance of 25Ω in the below circuit, Which of the following options is correct? (1) I1 = 1 (2) I2 = 1 I2 I3 I1 I3 (3) = 2 (4) = 1 I2 I4

Q18.Two radioactive elements 𝐴 and 𝐵 initially have same number of atoms. The half life of 𝐴 is same as the average life of 𝐵. If 𝜆𝐴 and 𝜆𝐵 are decay constants of 𝐴 and 𝐵 respectively, then choose the correct relation from the given options. (1) 𝜆𝐴ln2 = 𝜆𝐵 (2) 𝜆𝐴= 𝜆𝐵 (3) 𝜆𝐴= 𝜆𝐵ln2 (4) 𝜆𝐴= 2𝜆𝐵

Q18. The current flowing through R2 is : (1) 3 2 A (2) 12 A (3) 1 3 A (4) 14 A

Q18.The current flowing through a conductor connected across a source is 2 A and 1. 2 A at 0oC and 100oC respectively. The current flowing through the conductor at 50oC will be _____ × 102 mA .

Q18.The de Broglie wavelength of an electron having kinetic energy E is λ . If the kinetic energy of electron becomes E , then its de-Broglie wavelength will be: 4 (1) √2λ (2) λ √2 (3) λ (4) 2λ 2

Q18.Consider the following radioactive decay process: 𝛼 𝛽- 𝛾 𝛼 𝛽+ 𝛾 218𝐴84 ⟶𝐴1 ⟶𝐴2 ⟶𝐴3 ⟶𝐴4 ⟶𝐴5 ⟶𝐴6 The mass number and the atomic number of A6 are given by: (1) 210 and 82 (2) 210 and 84 (3) 210 and 80 (4) 211 and 80

Q18.If a copper wire is stretched to increase its length by 20% . The percentage increase in resistance of the wire is _____%.

Q18.The mass of proton, neutron and helium nucleus are respectively 1 . 0073 u, 1 . 0087 u and 4 . 0015u. The binding energy of helium nucleus is: (1) 14 . 2 MeV (2) 28 . 4 MeV (3) 56 . 8 MeV (4) 7 . 1 MeV